When drilling for oil, it has been customary to deposit drill cuttings, waste mud and runoff into a reserve pit—which is generally a large hole in the ground lined with plastic or some other water impermeable material to prevent liquids from leaching into the surrounding soil. In a typical reserve pit process the water is allowed to evaporate and then, once dried, the solids can typically be buried on site.
However, reserve pits often contain substantial quantities of contaminants such as petroleum hydrocarbons, diesel range organics, gasoline range organics, benzene and other harmful substances that can, over time, leach out into surrounding soil as a result of liner failure—even when proper drying and backfilling techniques have been employed. These contaminants can pollute water supplies and have devastating ecological effects on humans and wildlife. For these reasons, many drilling companies and government agencies are now actively seeking to reclaim former mining sites by cleansing the reserve pit soil.
Hydrogen peroxide (H2O2) is a known means for breaking down and treating a variety of contaminants including, but not limited to, chlorinated solvents; munitions; pesticides; petroleum residues; wood preservatives; etc. Current usages of hydrogen peroxide in connection with reserve pits are uneconomical and inefficient. In particular, the most prominent present methodologies are: 1) the contaminated soils are extracted and mixed with hydrogen peroxide in a surface mixer, leach pile, etc. and then redeposited (Ex-situ treatment); or, alternatively, 2) the soils are treated in place with sprayers, sprinklers or nozzle injectors (In-situ treatment). Both of these methodologies as currently practiced have significant inefficiencies and limitations. For example, the Ex-situ treatment requires large quantities of trucks and other heavy machinery to load and haul the materials off-site. This adds considerable expense and has a negative environmental impact as these trucks and machines often require large volumes of fuel and contribute to air pollution in their operation. Moreover, the sheer volume of trucks that such reclamation practices puts on the roads increases the likelihood of accidents simply as a matter of probabilities. The in-situ treatment is also less effective in that it does not allow for sufficient penetration and saturation of the soil with the hydrogen peroxide. Accordingly, the treatment process can fail to fully decontaminate the soil; or it takes considerably longer and costs more because repeat treatment is often necessary.
Soil shredders in combination with belt systems have been recently developed to improve exposure of contaminated soil to chemical treatments. However, these solutions have significant limitations. For example, while they improve soil penetration and saturation with the treatment chemicals, much of the soil still remains untouched and therefore untreated—meaning the process needs to be repeated requiring more additional time and expense. These prior art solutions also do not allow great flexibility in terms of adjusting treatment chemical concentrations. Current soil shredder systems also are prone to breakage and when they do break, key features are difficult to access and repair.
It would therefore be advantageous to have a soil treatment system and process that 1) maximizes exposure of the soil to the treatment chemical—e.g. the hydrogen peroxide solution; 2) allows greater saturation of the soil with the treatment chemicals while requiring less of that solution and is thereby substantially more efficient and less expensive in its operation; 3) and allows for instantaneous and precision adjustment of treatment chemical concentrations in response to field tests of both treated and pre-treated soil; and 4) has key components easily accessible such that they can readily be repaired or replaced as needed.
The present invention in its various embodiments addresses all the foregoing issues as well as others as described below.